beware installing a new cam. it will change things enough that i bet within 10k miles you'll have to have a valve job done on your heads, unless the new cams specs are the same as the worn out cams specs.
There is NO relationship to what your suggesting. Sorry, you've just chose to change the cams on 3 worn out engines. Those engines would have needed a valvejob in the next 10,000 miles regardless if you changed the cams or not. My Two Cents, Lorne
No, it happens. probably just lucky, or I'm unlucky. the valves get worn into a certain spot and suddenly you put in a higher lift cam, itll make the valves eat the valve guides up. they wouldnt have needed the valve job if i hadnt changed anything.
Swear on my kids it happened. one engine had 65k on it, one had 120k on it and one had 180k on it, they all did the same thing. only engine it didnt do it to, was a 400 i had, i put a cam in it and got 40k more out of it before i got rid of it. i just dont like doing it cuz it sucks to take the engine down that far, twice in a relatively short period.
I thought of an analogy, tho bear with me.
everybody knows what the ridge is at the top of a cylinder in an older engine. you have to use a reamer to get the piston out. these ridges (not as big tho, exist in worn valves and OE rocker arms)
I know this wouldnt work in real life but say you put longer rods in the engine and thats it. dont worry about clearancing and oil pans and stuff, as this wouldnt work anyway. but if you did nothing to the ridge at the top of the cylinder and suddenly you want the piston to run higher in its bore than it used to, it would hit that that ridge and cause damage. while the valve wont get that dramatic of damage, suddenly your making them hit that ridge they've worn in themselves against the cast iron guides in the heads.
when I changed cams, the valve runners were pretty clean and then not long after when i burnt a valve the intake and exhaust runners were gunked up from the oil leaking by into the intake runners, which carboned up and chunks of that stuff eventually kept an intake valve from closing all the way and then not seating right i ended up with a burnt valve.
1
